binutils-gdb/gdb/inftarg.c

/* Target-vector operations for controlling Unix child processes, for GDB.

   Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999,
   2000, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.

   Contributed by Cygnus Support.

   ## Contains temporary hacks..

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.  */

#include "defs.h"
#include "frame.h"		/* required by inferior.h */
#include "inferior.h"
#include "target.h"
#include "gdbcore.h"
#include "command.h"
#include "gdb_stat.h"
#include <signal.h>
#include <sys/types.h>
#include <fcntl.h>
#include "observer.h"
#include "gdb_wait.h"
#include "inflow.h"

extern struct symtab_and_line *child_enable_exception_callback (enum
								exception_event_kind,
								int);

extern struct exception_event_record
  *child_get_current_exception_event (void);

extern void _initialize_inftarg (void);

static void child_prepare_to_store (void);

#ifndef CHILD_WAIT
static ptid_t child_wait (ptid_t, struct target_waitstatus *);
#endif /* CHILD_WAIT */

static void child_open (char *, int);

static void child_files_info (struct target_ops *);

static void child_detach (char *, int);

static void child_attach (char *, int);

#if !defined(CHILD_POST_ATTACH)
extern void child_post_attach (int);
#endif

static void ptrace_me (void);

static void ptrace_him (int);

static void child_create_inferior (char *, char *, char **, int);

static void child_mourn_inferior (void);

static int child_can_run (void);

static void child_stop (void);

#ifndef CHILD_THREAD_ALIVE
int child_thread_alive (ptid_t);
#endif

static void init_child_ops (void);

extern char **environ;

int child_suppress_run = 0;	/* Non-zero if inftarg should pretend not to
				   be a runnable target.  Used by targets
				   that can sit atop inftarg, such as HPUX
				   thread support.  */

#ifndef CHILD_WAIT

/* Wait for child to do something.  Return pid of child, or -1 in case
   of error; store status through argument pointer OURSTATUS.  */

static ptid_t
child_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
{
  int save_errno;
  int status;
  char *execd_pathname = NULL;
  int exit_status;
  int syscall_id;
  enum target_waitkind kind;
  int pid;

  do
    {
      set_sigint_trap ();	/* Causes SIGINT to be passed on to the
				   attached process. */
      set_sigio_trap ();

      pid = wait (&status);

      save_errno = errno;

      clear_sigio_trap ();

      clear_sigint_trap ();

      if (pid == -1)
	{
	  if (save_errno == EINTR)
	    continue;

	  fprintf_unfiltered (gdb_stderr, "Child process unexpectedly missing: %s.\n",
			      safe_strerror (save_errno));

	  /* Claim it exited with unknown signal.  */
	  ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
	  ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
	  return pid_to_ptid (-1);
	}

      /* Did it exit?
       */
      if (target_has_exited (pid, status, &exit_status))
	{
	  /* ??rehrauer: For now, ignore this. */
	  continue;
	}

      if (!target_thread_alive (pid_to_ptid (pid)))
	{
	  ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
	  return pid_to_ptid (pid);
	}
      } while (pid != PIDGET (inferior_ptid)); /* Some other child died or stopped */

  store_waitstatus (ourstatus, status);
  return pid_to_ptid (pid);
}
#endif /* CHILD_WAIT */

#ifndef CHILD_THREAD_ALIVE

/* Check to see if the given thread is alive.

   FIXME: Is kill() ever the right way to do this?  I doubt it, but
   for now we're going to try and be compatable with the old thread
   code.  */
int
child_thread_alive (ptid_t ptid)
{
  pid_t pid = PIDGET (ptid);

  return (kill (pid, 0) != -1);
}

#endif

/* Attach to process PID, then initialize for debugging it.  */

static void
child_attach (char *args, int from_tty)
{
  char *exec_file;
  int pid;
  char *dummy;

  if (!args)
    error_no_arg (_("process-id to attach"));

  dummy = args;
  pid = strtol (args, &dummy, 0);
  /* Some targets don't set errno on errors, grrr! */
  if ((pid == 0) && (args == dummy))
      error (_("Illegal process-id: %s."), args);
  
  if (pid == getpid ())	/* Trying to masturbate? */
    error (_("I refuse to debug myself!"));
  
  if (from_tty)
    {
      exec_file = (char *) get_exec_file (0);
      
      if (exec_file)
	printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
			   target_pid_to_str (pid_to_ptid (pid)));
      else
	printf_unfiltered (_("Attaching to %s\n"),
			   target_pid_to_str (pid_to_ptid (pid)));
      
      gdb_flush (gdb_stdout);
    }

  attach (pid);
  
  inferior_ptid = pid_to_ptid (pid);
  push_target (&deprecated_child_ops);

  /* Do this first, before anything has had a chance to query the
     inferior's symbol table or similar.  */
  observer_notify_inferior_created (&current_target, from_tty);
}

#if !defined(CHILD_POST_ATTACH)
void
child_post_attach (int pid)
{
  /* This version of Unix doesn't require a meaningful "post attach"
     operation by a debugger.  */
}
#endif

/* Take a program previously attached to and detaches it.
   The program resumes execution and will no longer stop
   on signals, etc.  We'd better not have left any breakpoints
   in the program or it'll die when it hits one.  For this
   to work, it may be necessary for the process to have been
   previously attached.  It *might* work if the program was
   started via the normal ptrace (PTRACE_TRACEME).  */

static void
child_detach (char *args, int from_tty)
{
  int siggnal = 0;
  int pid = PIDGET (inferior_ptid);
  
  if (from_tty)
    {
      char *exec_file = get_exec_file (0);
      if (exec_file == 0)
	exec_file = "";
      printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
			 target_pid_to_str (pid_to_ptid (pid)));
      gdb_flush (gdb_stdout);
    }
  if (args)
    siggnal = atoi (args);
  
  detach (siggnal);
  
  inferior_ptid = null_ptid;
  unpush_target (&deprecated_child_ops);
}

/* Get ready to modify the registers array.  On machines which store
   individual registers, this doesn't need to do anything.  On machines
   which store all the registers in one fell swoop, this makes sure
   that registers contains all the registers from the program being
   debugged.  */

static void
child_prepare_to_store (void)
{
#ifdef CHILD_PREPARE_TO_STORE
  CHILD_PREPARE_TO_STORE ();
#endif
}

/* Print status information about what we're accessing.  */

static void
child_files_info (struct target_ops *ignore)
{
  printf_unfiltered (_("\tUsing the running image of %s %s.\n"),
      attach_flag ? "attached" : "child", target_pid_to_str (inferior_ptid));
}

static void
child_open (char *arg, int from_tty)
{
  error (_("Use the \"run\" command to start a Unix child process."));
}

/* Stub function which causes the inferior that runs it, to be ptrace-able
   by its parent process.  */

static void
ptrace_me (void)
{
  /* "Trace me, Dr. Memory!" */
  call_ptrace (0, 0, (PTRACE_TYPE_ARG3) 0, 0);
}

/* Stub function which causes the GDB that runs it, to start ptrace-ing
   the child process.  */

static void
ptrace_him (int pid)
{
  push_target (&deprecated_child_ops);

  /* On some targets, there must be some explicit synchronization
     between the parent and child processes after the debugger
     forks, and before the child execs the debuggee program.  This
     call basically gives permission for the child to exec.
   */

  target_acknowledge_created_inferior (pid);

  /* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h,
   * and will be 1 or 2 depending on whether we're starting
   * without or with a shell.
   */
  startup_inferior (START_INFERIOR_TRAPS_EXPECTED);

  /* On some targets, there must be some explicit actions taken after
     the inferior has been started up.
   */
  target_post_startup_inferior (pid_to_ptid (pid));
}

/* Start an inferior Unix child process and sets inferior_ptid to its pid.
   EXEC_FILE is the file to run.
   ALLARGS is a string containing the arguments to the program.
   ENV is the environment vector to pass.  Errors reported with error().  */

static void
child_create_inferior (char *exec_file, char *allargs, char **env,
		       int from_tty)
{
  fork_inferior (exec_file, allargs, env, ptrace_me, ptrace_him, NULL, NULL);

  /* We are at the first instruction we care about.  */
  observer_notify_inferior_created (&current_target, from_tty);
  /* Pedal to the metal... */
  proceed ((CORE_ADDR) -1, TARGET_SIGNAL_0, 0);
}

#if !defined(CHILD_POST_STARTUP_INFERIOR)
void
child_post_startup_inferior (ptid_t ptid)
{
  /* This version of Unix doesn't require a meaningful "post startup inferior"
     operation by a debugger.
   */
}
#endif

#if !defined(CHILD_ACKNOWLEDGE_CREATED_INFERIOR)
void
child_acknowledge_created_inferior (int pid)
{
  /* This version of Unix doesn't require a meaningful "acknowledge created inferior"
     operation by a debugger.
   */
}
#endif


#if !defined(CHILD_INSERT_FORK_CATCHPOINT)
void
child_insert_fork_catchpoint (int pid)
{
  /* This version of Unix doesn't support notification of fork
     events.  */
}
#endif

#if !defined(CHILD_REMOVE_FORK_CATCHPOINT)
int
child_remove_fork_catchpoint (int pid)
{
  /* This version of Unix doesn't support notification of fork events.  */
  return 0;
}
#endif

#if !defined(CHILD_INSERT_VFORK_CATCHPOINT)
void
child_insert_vfork_catchpoint (int pid)
{
  /* This version of Unix doesn't support notification of vfork
     events.  */
}
#endif

#if !defined(CHILD_REMOVE_VFORK_CATCHPOINT)
int
child_remove_vfork_catchpoint (int pid)
{
  /* This version of Unix doesn't support notification of vfork events.  */
  return 0;
}
#endif

#if !defined(CHILD_FOLLOW_FORK)
int
child_follow_fork (struct target_ops *ops, int follow_child)
{
  /* This version of Unix doesn't support following fork or vfork events.  */
  return 0;
}
#endif

#if !defined(CHILD_INSERT_EXEC_CATCHPOINT)
void
child_insert_exec_catchpoint (int pid)
{
  /* This version of Unix doesn't support notification of exec
     events.  */
}
#endif

#if !defined(CHILD_REMOVE_EXEC_CATCHPOINT)
int
child_remove_exec_catchpoint (int pid)
{
  /* This version of Unix doesn't support notification of exec events.  */
  return 0;
}
#endif

#if !defined(CHILD_REPORTED_EXEC_EVENTS_PER_EXEC_CALL)
int
child_reported_exec_events_per_exec_call (void)
{
  /* This version of Unix doesn't support notification of exec events.
   */
  return 1;
}
#endif

#if !defined(CHILD_HAS_EXITED)
int
child_has_exited (int pid, int wait_status, int *exit_status)
{
  if (WIFEXITED (wait_status))
    {
      *exit_status = WEXITSTATUS (wait_status);
      return 1;
    }

  if (WIFSIGNALED (wait_status))
    {
      *exit_status = 0;		/* ?? Don't know what else to say here. */
      return 1;
    }

  /* ?? Do we really need to consult the event state, too?  Assume the
     wait_state alone suffices.
   */
  return 0;
}
#endif


static void
child_mourn_inferior (void)
{
  unpush_target (&deprecated_child_ops);
  generic_mourn_inferior ();
}

static int
child_can_run (void)
{
  /* This variable is controlled by modules that sit atop inftarg that may layer
     their own process structure atop that provided here.  hpux-thread.c does
     this because of the Hpux user-mode level thread model.  */

  return !child_suppress_run;
}

/* Send a SIGINT to the process group.  This acts just like the user typed a
   ^C on the controlling terminal.

   XXX - This may not be correct for all systems.  Some may want to use
   killpg() instead of kill (-pgrp). */

static void
child_stop (void)
{
  kill (-inferior_process_group, SIGINT);
}

#if !defined(CHILD_ENABLE_EXCEPTION_CALLBACK)
struct symtab_and_line *
child_enable_exception_callback (enum exception_event_kind kind, int enable)
{
  return (struct symtab_and_line *) NULL;
}
#endif

#if !defined(CHILD_GET_CURRENT_EXCEPTION_EVENT)
struct exception_event_record *
child_get_current_exception_event (void)
{
  return (struct exception_event_record *) NULL;
}
#endif


#if !defined(CHILD_PID_TO_EXEC_FILE)
char *
child_pid_to_exec_file (int pid)
{
  /* This version of Unix doesn't support translation of a process ID
     to the filename of the executable file.
   */
  return NULL;
}
#endif

char *
child_core_file_to_sym_file (char *core)
{
  /* The target stratum for a running executable need not support
     this operation.
   */
  return NULL;
}

/* Perform a partial transfer to/from the specified object.  For
   memory transfers, fall back to the old memory xfer functions.  */

static LONGEST
child_xfer_partial (struct target_ops *ops, enum target_object object,
		    const char *annex, gdb_byte *readbuf,
		    const gdb_byte *writebuf, ULONGEST offset, LONGEST len)
{
  switch (object)
    {
    case TARGET_OBJECT_MEMORY:
      if (readbuf)
	return child_xfer_memory (offset, readbuf, len, 0/*write*/,
				  NULL, ops);
      if (writebuf)
	return child_xfer_memory (offset, (void *) writebuf, len, 1/*write*/,
				  NULL, ops);
      return -1;

    case TARGET_OBJECT_UNWIND_TABLE:
#ifndef NATIVE_XFER_UNWIND_TABLE
#define NATIVE_XFER_UNWIND_TABLE(OPS,OBJECT,ANNEX,WRITEBUF,READBUF,OFFSET,LEN) (-1)
#endif
      return NATIVE_XFER_UNWIND_TABLE (ops, object, annex, readbuf, writebuf,
				       offset, len);

    case TARGET_OBJECT_AUXV:
#ifndef NATIVE_XFER_AUXV
#define NATIVE_XFER_AUXV(OPS,OBJECT,ANNEX,WRITEBUF,READBUF,OFFSET,LEN) (-1)
#endif
      return NATIVE_XFER_AUXV (ops, object, annex, readbuf, writebuf,
			       offset, len);

    default:
      return -1;
    }
}

#if !defined(CHILD_PID_TO_STR)
char *
child_pid_to_str (ptid_t ptid)
{
  return normal_pid_to_str (ptid);
}
#endif

static void
init_child_ops (void)
{
  deprecated_child_ops.to_shortname = "child";
  deprecated_child_ops.to_longname = "Unix child process";
  deprecated_child_ops.to_doc = "Unix child process (started by the \"run\" command).";
  deprecated_child_ops.to_open = child_open;
  deprecated_child_ops.to_attach = child_attach;
  deprecated_child_ops.to_post_attach = child_post_attach;
  deprecated_child_ops.to_detach = child_detach;
  deprecated_child_ops.to_resume = child_resume;
  deprecated_child_ops.to_wait = child_wait;
  deprecated_child_ops.to_fetch_registers = fetch_inferior_registers;
  deprecated_child_ops.to_store_registers = store_inferior_registers;
  deprecated_child_ops.to_prepare_to_store = child_prepare_to_store;
  deprecated_child_ops.deprecated_xfer_memory = child_xfer_memory;
  deprecated_child_ops.to_xfer_partial = child_xfer_partial;
  deprecated_child_ops.to_files_info = child_files_info;
  deprecated_child_ops.to_insert_breakpoint = memory_insert_breakpoint;
  deprecated_child_ops.to_remove_breakpoint = memory_remove_breakpoint;
  deprecated_child_ops.to_terminal_init = terminal_init_inferior;
  deprecated_child_ops.to_terminal_inferior = terminal_inferior;
  deprecated_child_ops.to_terminal_ours_for_output = terminal_ours_for_output;
  deprecated_child_ops.to_terminal_save_ours = terminal_save_ours;
  deprecated_child_ops.to_terminal_ours = terminal_ours;
  deprecated_child_ops.to_terminal_info = child_terminal_info;
  deprecated_child_ops.to_kill = kill_inferior;
  deprecated_child_ops.to_create_inferior = child_create_inferior;
  deprecated_child_ops.to_post_startup_inferior = child_post_startup_inferior;
  deprecated_child_ops.to_acknowledge_created_inferior = child_acknowledge_created_inferior;
  deprecated_child_ops.to_insert_fork_catchpoint = child_insert_fork_catchpoint;
  deprecated_child_ops.to_remove_fork_catchpoint = child_remove_fork_catchpoint;
  deprecated_child_ops.to_insert_vfork_catchpoint = child_insert_vfork_catchpoint;
  deprecated_child_ops.to_remove_vfork_catchpoint = child_remove_vfork_catchpoint;
  deprecated_child_ops.to_follow_fork = child_follow_fork;
  deprecated_child_ops.to_insert_exec_catchpoint = child_insert_exec_catchpoint;
  deprecated_child_ops.to_remove_exec_catchpoint = child_remove_exec_catchpoint;
  deprecated_child_ops.to_reported_exec_events_per_exec_call = child_reported_exec_events_per_exec_call;
  deprecated_child_ops.to_has_exited = child_has_exited;
  deprecated_child_ops.to_mourn_inferior = child_mourn_inferior;
  deprecated_child_ops.to_can_run = child_can_run;
  deprecated_child_ops.to_thread_alive = child_thread_alive;
  deprecated_child_ops.to_pid_to_str = child_pid_to_str;
  deprecated_child_ops.to_stop = child_stop;
  deprecated_child_ops.to_enable_exception_callback = child_enable_exception_callback;
  deprecated_child_ops.to_get_current_exception_event = child_get_current_exception_event;
  deprecated_child_ops.to_pid_to_exec_file = child_pid_to_exec_file;
  deprecated_child_ops.to_stratum = process_stratum;
  deprecated_child_ops.to_has_all_memory = 1;
  deprecated_child_ops.to_has_memory = 1;
  deprecated_child_ops.to_has_stack = 1;
  deprecated_child_ops.to_has_registers = 1;
  deprecated_child_ops.to_has_execution = 1;
  deprecated_child_ops.to_magic = OPS_MAGIC;
}

void
_initialize_inftarg (void)
{
#ifdef HAVE_OPTIONAL_PROC_FS
  char procname[32];
  int fd;

  /* If we have an optional /proc filesystem (e.g. under OSF/1),
     don't add ptrace support if we can access the running GDB via /proc.  */
#ifndef PROC_NAME_FMT
#define PROC_NAME_FMT "/proc/%05d"
#endif
  sprintf (procname, PROC_NAME_FMT, getpid ());
  fd = open (procname, O_RDONLY);
  if (fd >= 0)
    {
      close (fd);
      return;
    }
#endif

  init_child_ops ();
  add_target (&deprecated_child_ops);
}